There is often a requirement for camera equipment to be tilted about a horizontal axis using a head which can hold the equipment balanced at any desired angle about the horizontal axis. Whilst a manual mechanism can be used, in which the camera is set at the desired angle and then the head is clamped at that angle, this is unsatisfactory and cumbersome and is not very useful for professional purposes.
Many counter-balancing mechanisms have been proposed in the past but up to now it has been found very difficult to obtain a counter-balancing mechanism which effectively counter-balances a load (which can be fairly substantial, up to around 50 kilograms for a camera for example) at virtually any desire angle. Referring to FIG. 1, if a camera of load L is rotated about a horizontal axis A through a desired angle then the torque at any angle is equal to the load L times the horizontal distance L of the load from the axis and this increases generally sinusoidally as the angle from the vertical increases. The counter-balancing mechanism is required to counteract this and, since it is not a linear function, this is difficult to achieve within a package of acceptable size/mass.
Furthermore, allowance must also be made first for variations in the weight of an item to be placed upon the support and tilted, and secondly for variations in the position of the centre of gravity of an item (for example, a camera mounted on a tripod may have its centre of gravity which is not coincident with the point which will be mounted directly above the centre of the tripod).
The present invention arose in an attempt to provide an improved counter-balancing mechanism.